Porous glass ceramics are widely used for various applications such as heat and acoustic insulation and building facade materials. The porous glass ceramics are mainly used for manufacturing tiles due to its properties such as, but not limited to, hardness, mechanical strength, durability and insulation.
Generally, glass ceramics are produced using a two steps process. In first step, a glass is produced by a glass manufacturing process using different types of raw materials. During the second step, the glass is melted and cast into a mold or shaped using any techniques known to those ordinarily skilled in the art. The molten glass is cooled down and thereafter reheated to partly crystallize the glass during the second step. For preparing the porous glass ceramics, the molten glass is foamed with gas generated in situ. Alternatively, foaming agents or pore-forming agents such as, but not limited to, silicon carbide (SiC) particles and carbon particles are used to generate pores in the glass ceramics.
An alternative method for manufacturing glass ceramics includes sintering and crystallizing glass particles of suitable composition. Waste-derived glass can also be used as a raw material for preparing the porous glass ceramics. However, the foaming of waste-derived glasses is complicated due to tendency of the glass being crystallized on heating. Extensive crystallization of the glass on heating leads to problems in homogeneity and reproducibility of an overall foam morphology. Sintering temperature needs to be adjusted well above crystallization temperature and high heating rates are required to force the glass to sinter before extensive crystallization. The high heating rates required to force the glass to sinter before extensive crystallization consumes high amount of energy. Moreover, the composition of glass used as a starting material needs to be accurately engineered in order to control crystallization tendency of the glass such that surface crystallization and bulk crystallization is balanced. Further, the porous glass ceramics produced using the conventional method exhibit only few desired mechanical and chemical properties.
Additionally, industrial wastes such as pozzolanic wastes, fly ash, cullet, etc are immobilized by disposal in land-fills or immobilized in cement industries. Handling and disposal of such industrial wastes may require additional cost and is also hazardous to the environment.
Therefore, there is a need to develop a method for manufacturing porous glass ceramics which is environment friendly, cost effective and has superior mechanical and chemical properties.